Members of Guns N’ Roses and Nirvana haven’t always been the best of pals. Back in the ’90s, the Seattle grunge rockers, less than impressed with GNR’s sleazy swagger, turned down an invitation to do a joint stadium tour. At the 1992 MTV Video Music Awards, Kurt Cobain and wife Courtney Love even got into a minor spat with Axl Rose over his Godfather-esque getup.

These days, however, members of the former mega bands are on better terms. In fact, the two groups’ ex-bass players actually joined forces recently to belt out a rather unorthodox interpretation of “Sweet Child O’ Mine.” Their performance, which had Duff McKagan of GNR on bass and Krist Novoselic of Nirvana rocking out on an accordion, took place Sunday at Seattle’s Neptune Theatre during the release of McKagan’s second book, “How To Be A Man: (and other illusions).”

“Wow, there’s a lot going on there–two hands,” McKagan remarked at the end of their six-minute set.

“You use two hands on the bass, too,” joked Novoselic. “I know how hard it is to play bass–don’t tell me. That song doesn’t even have a lot of bass lines. Where’s Axl Rose when you need him?”

Novoselic has also played accordion on the Foo Fighters’ song “I Should Have Known” off their album Wasting Light.

Their rendition of the hard rock classic comes in the wake of a claim by the Aussie entertainment site Max TV that GNR may have ripped their tune off from a 1981 song called “Unpublished Critics” by the Australian Crawl.

Co-written with author Chris Kornelis, McKagan’s new book reflects on life lessons he’s learned from being a rock-and-roller with Guns N’ Roses, Velvet Revolver and Walking Papers, as well as his thoughts on being a husband and father.

Fans can order a copy of the Da Capo Press publication, which came out May 12, here.

Along with the book, the bassist has released a three-song EP, too. Also titled “How To Be A Man,” it explores similar themes and features the talents of his old bandmate Izzy Stradlin, Alice in Chains’ Jerry Cantrell and Stone Sours’ Roy Mayorga.